1. Field of the Invention
The present invention relates to an industrial robot, and particularly to a robot having a function of drawing a fitting part from a receiving part.
2. Description of Related Art
It has already known to automatically fit a workpiece in another workpiece using a force-controlling robot capable of operating under force control. Further, a method of fitting a fitting part in a receiving part with their phases matched with each other using the force-controlling robot is disclosed in Japanese Laid-Open Patent Publication No. 9-136279.
There is a case where the fitting operation is not completed because of an inappropriate fitting state in performing the fitting operation using the force-controlling robot. In such case, conventionally, an error is indicated during the fitting operation and the robot is stopped, and then a restoration operation is performed manually.
Further, conventionally, when an assembly constituted by a plurality of parts is to be disassembled, drawing a fitted part out of the assembly to be disassembled is performed manually and is not automatically performed using a robot.
In the operation of fitting a workpiece into another workpiece using a force-controlling robot, if the fitting operation is not completed and the robot stops due to an error occurring in the fitting operation, it takes time and labor to perform the manual restoration and such manual restoration is very cumbersome to cause lowering of the overall operation efficiency.
Further, it is desirable if the operation of drawing a fitted part out of the assembly can be automatically performed by a robot instead of the manual operation when disassembling an assembly constituted by a plurality of parts.
An object of the present invention is to provide a force-controlling robot having a function of drawing a fitting part from a receiving part and a fitting and drawing method using the force-controlling robot.
A force-controlling robot of the present invention has a force sensor at a wrist portion thereof to insert a fitting part to be fitted into an object of fitting while performing a force control, and has a function of drawing the fitting part from the object of fitting by moving the fitting part in a direction opposite to an inserting direction when the fitting operation is not progressed by a predetermined distance or to a predetermined position within a predetermined time period. The moving of the fitting part in the direction opposite to the inserting direction can be achieved by changing parameters set for the fitting operation. The drawing operation and the fitting operation are repeatedly executed when the fitting operation is not completed.
Further, a force-controlling robot of the present invention has a function of holding a fitted part in the assembled parts by a robot hand while performing a force control using the force sensor, and drawing the fitted part out of the assembled parts while performing the force control using the force sensor.
Furthermore, the present invention provides a fitting/drawing method in which the drawing operation is performed in the middle of the fitting operation when the fitting operation does not progress, and a drawing/disassembling method for drawing a fitted part out of assembled parts.